What is the net force here and what direction will the object accelerate ?

There is 100 N pushing the box to the right and 10 N pushing the box to the left
 

since there is force being applied in opposite directions, the net force is found by subtracting the 2

100 - 10 = 90 N ( Net Force)

and because the higher force is pushing the box to the right, the direction will accelerate to the right.